Fast two-bit operations in inductively coupled flux qubits

TL;DR

This paper proposes a practical method to achieve fast two-qubit operations in flux qubits by effectively coupling them through a common inductance, overcoming the challenge of weak interbit coupling in distant qubits.

Contribution

It introduces an experimentally feasible approach to strongly couple flux qubits with small inductance, enabling two-bit operations comparable in speed to one-bit operations.

Findings

Strong interbit coupling achieved with small inductance

Two-bit operations can be as fast as one-bit operations

Flux dependence of state transitions analyzed

Abstract

A central problem for implementing efficient quantum computing is how to realize fast operations (both one- and two-bit ones). However, this is difficult to achieve for a collection of qubits, especially for those separated far away, because the interbit coupling is usually much weaker than the intrabit coupling. Here we present an experimentally feasible method to effectively couple two flux qubits via a common inductance and treat both single and coupled flux qubits with more realistic models which include the loop inductance. The main advantage of our proposal is that a strong interbit coupling can be achieved using a small inductance, so that two-bit operations as fast as one-bit ones can be easily realized. We also show the flux dependence of the transitions between states for the coupled flux qubits.